For forming a bead filler for example, which is illustrated in FIG. 14 and is assembled into bead portions of a tire, following method is generally taken. Firstly, a ribbon of to-be-vulcanized rubber material is extruded in a predetermined sectional shape by an extruder, and then cut into a certain length. Subsequently, such cut ribbon of the rubber is bonded onto outer circumferential face of a bead's reinforcing member such as a wire that has been preliminary shaped as a ring, while ends of the cut ribbon of the rubber are bonded together.
In above method of cutting into a certain length and then bonding, precision for forming is labile due to surging or pulsation during extrusion or bonding. This might cause fluctuation and irregularities in weight and/or uniformity of tire products and thus adversely affect quality assurance.
In a case shown in FIG. 15 for example, an elongated rubber body “a” is extruded in a substantially triangular or wedge-shaped cross section that is elongated or widened in a radial direction of a tire. The elongated rubber body “a” is then wound, and is cut accordingly, around an outer circumferential face of the bead's reinforcing member 2, followed by butt-wise joining and bonding of ends “e” of the cut rubber member. In this case, tensile strain is formed all over the elongated rubber body “a” as highest in its outer periphery. Thus, the elongated rubber body “a” is prone to detaching and parting from the bead's reinforcing member, the more the closer to the ends “e”. The detaching and parting is made as indicated by chain lines in FIG. 15 for example, thus damaging the balance of tire product. Moreover, the elongated rubber body “a” forms a jutting out at joined ends “e”, thus causing irregularity in rubber distribution and the like. Therefore, uniform ones of tire's annular members are not obtainable. These drawbacks become more apparent when width-wise radial dimension or height “h” of the tire's annular member is increased. With increase of the width-wise radial dimension, the tire's annular member becomes more liable to collapse; and hence, the radial dimension or height “h” should be restricted.
In otherwise, the rubber member having been extruded and cut in a certain length is wound around a drum to form a ring or tube and then expanded in radial direction. In this case, expanding at outer periphery of the rubber member is large, thus shaping and dimensions of the rubber member becomes labile.
In view of above, various methods for overcoming the drawbacks attributed to the above-mentioned cutting into a given size have been proposed. For example, JP-A-2002-187218 discloses a method for forming a bead filler or the like in an annular shape, in which a bead's reinforcing member is placed on a rotating plate; and extruded rubber body is supplied to the outer circumferential face of the bead's reinforcing member while rotating the plate. Subsequently, the rubber body is pressed and formed into a given shape using a tool and, at the same time, is bonded to the bead's reinforcing member while ends of the formed rubber member are joined together. In this method of forming a bead filler, rubber body is extruded onto a rotating plate and almost simultaneously a tool is applied as to scrape the rubber body. Thus, shaping is prone to being erratic and high precision is not achieved. Moreover, seam portion of joined ends may also be erratic and might have rubber residue or fragment not used.
Meanwhile, JP-A-1989-314151 discloses a method for forming a tire's annular member having a shape extended in the radial direction such as a sidewall, in which an extruded rubber body is processed by calendar rollers and then is supplied to a rotating annular support shaped as a truncated cone. Thus formed rubber sheets or strips are wound around the annular support to form a tire's annular member. This method requires the calendar roller; and forming of the tire's annular member is not made in a wound state. Thus, shape or dimensions of the tire's annular member is unstable or may be erratic and satisfactory precision is not achieved.
In view of the above, it is aimed to form a tire's annular member expanded predominantly in a radial direction such as a bead filler, a sidewall, or the like, by a relatively simple equipment and at high precision; and thereby to reduce irregularities in weight and uniformity of tire product, thus achieving high quality of the tire product.
In view of the above, it is aimed to provide a method and device for manufacturing a tire's annular member having a stretch mainly in radial direction such as a bead filler and a side wall; by use of simple devices and simple way of pressing and with high precision and easiness, for achieving tire products of high quality with suppressed fluctuation in mass and/or uniformity.